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Reduced Body Size is a Positive Response to Climate Change

Surveying 85 unique sites on the western borders of North Carolina and Virginia, biologist Nicholas Caruso and his team collected data on adult specimens of Appalachian woodland salamanders (genus Plethodon). The results showed a reduction in salamander body size in accordance with lower climate temperatures. Because woodland salamanders are lungless they breathe through their skin and require a moist environment for survival. The authors used historical and present-day data to model the changes in body size of 15 species of salamanders over the past 55 years. The dataset included 9,450 adult body size measurements from 102 populations of the 15 different species of salamanders. An 8% reduction in the average salamander size was found in all of the species over the 55-year study (Caruso et al, 2014). The reduction in body size reveals the plasticity of organisms to adapt to changes in climate. Because body size is directly linked to diet and foraging behavior, growth rates are also affected. Smaller body size means less surface area, and less loss of moisture through cutaneous responses. Also, the salamanders that were surveyed have demonstrated an increase in metabolism.

In a warming world, animals will need to adapt in order to survive. The woodland salamanders have revealed that, at lower latitudes of North America where the forests have become drier over the last 55 years, they are at a low risk of extinction because of their ability to respond positively to climate change. The authors were not able to determine if the reduction in body size was due to changes in energetics caused by growth response, or if it was due to natural selection of a reduced size in conjunction with limited energy. However, the authors also speculate that higher temperatures may affect the developmental stage of salamanders, causing retardation in growth without negatively affecting adult survivorship.